Air brake systems are used in trucks or other heavy duty vehicles for providing “failsafe” vehicle brake operation. Generally, air brake systems have two modes of operating. The first mode is a failsafe mode used for the emergency brake function. The second mode is used under normal operation and compressed air to activate the braking mechanism. If a loss of compressed air pressure occurs, the failsafe mechanisms engage the brakes attempting to lock the wheels in position and stop the progress of the vehicle. Under normal operation, air that is compressed by a compressor in the vehicle is directed by the vehicle operator to actuators. The actuators are induced to move by the delivered compressed air. When the intended results are achieved and the braking function is no longer needed, the system exhausts the contained pressure within the actuator. The actuator returns to the original position and the braking mechanisms are disengaged. Thus, the compressed air provides and maintains air under pressure to the brakes to ensure fails-safe vehicle brake operation.
The compressed air that leaves the compressor is typically not suitable to be supplied directly to the brake system for several reasons. The first reason is that the compressed air contains oil. The compressor is supplied with oil from the vehicle engine that is used for lubrication of bearings and other compressor components. Lubricating oil within the compressor is difficult to contain. It contaminates the compressed air stream delivered by the compressor. The second reason is that the compressor ingests humid air from the surrounding environment. The humid air is compressed and delivered by the compressor to the system.
Conventional air brake systems use a dryer located downstream of the air compressor to dry the pressurized air prior to delivery of the air to the brakes. The air is dried for efficiency and to prevent damage to the downstream components. However, the dryer typically houses a desiccant material that may become contaminated with the oil entrained in the compressed air. Thus, an improved filter assembly is desirable.